Redux thing into subscribe method

JavaScript
1

Tell us what’s happening:

Your code so far


const ADD = 'ADD';

const reducer = (state = 0, action) => {
switch(action.type) {
  case ADD:
    return state + 1;
  default:
    return state;
}
};

const store = Redux.createStore(reducer);

// global count variable:
let count = 0;

// change code below this line
store.subscribe(count+1);
// change code above this line

store.dispatch({type: ADD});
console.log(count);
store.dispatch({type: ADD});
console.log(count);
store.dispatch({type: ADD});
console.log(count);

Your browser information:

User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.61 Safari/537.36.

Challenge: Register a Store Listener

Link to the challenge:

2

You should pass a function to store.subscribe();

1 Like
3

Normally, the redux working process is as follows:

  1. An action is dispatched to the store.
  2. The store received the action and send it to the reducer.
  3. The reducer updates the state in the store.
  4. The store notifies subscribers that the state is changed by calling the callback function provided by the subscriber.
  5. The subscriber updates the UI.

Callback function is simply a function for receivers to call it back later.

example 1:
store.subscribe(() => console.log(“something change is the store.”))

example 2:
function x(){
console.log(“something change is the store.”);
}
store.subscribe(x);

example 3:
store.subscribe(function(){ console.log(“something change is the store.”); });

1 Like